Clinical Characteristics of Atopic Dermatitis in Korean School-Aged Children and Adolescents According to Onset Age and Severity

Background: Atopic dermatitis (AD) is a heterogeneous disease with different age of onset, disease course, clinical symptoms, severity, and risk of comorbidity. The characteristics of children with AD also vary by age or country. However, little is known about the clinical characteristics of AD in Korean school-aged children and adolescents. Furthermore, there are few studies on phenotypic differences according to onset age. This study aimed to explore the clinical characteristics and phenotypes according to onset age and severity of AD in children and adolescents in Korea. Methods: All patients aged 6-18 years who presented to 18 hospitals nationwide were surveyed. The patients were examined for disease severity by pediatric allergy specialists, and data on history of other allergic diseases, familial allergy history, onset age, trigger factors, lesion sites, treatment history and quality of life were collected. The results of the patient's allergy test were also analyzed. The patients were classified into infancy-onset (< 2 years of age), preschoolonset (2-5 years of age), and childhood-onset (>= 6 years ofage) groups. Study population was analyzed for clinical features according to onset-age groups and severity groups. Results: A total of 258 patients with a mean age of10.62 +/- 3.18 years were included in the study. Infancy-onset group accounted for about 60% of all patients and presented significantly more other allergic diseases, such as allergic rhinitis and asthma (P= 0.002 and P= 0.001, respectively). Food allergy symptoms and diagnoses were highly relevant to both earlier onset and more severe group. Inhalant allergen sensitization was significantly associated with both infancy-onset group and severe group (P= 0.012 and P= 0.024, respectively). A family history of food allergies was significantly associated with infancy-onset group (P= 0.036). Severe group was significantly associated with a family history of AD, especially a paternal history of All (P= 0.048 and P= 0.004, respectively). Facial (periorbital, ear, and cheek) lesions, periauricular fissures, hand/foot eczema, and xerosis were associated with infancy-onset group. The earlier the onset of All, the poorer the quality of life (P= 0.038). Systemic immunosuppressants were used in only 9.6% of the patients in the severe group. Conclusion: This study analyzed the clinical features of AD in Korean children and adolescents through a multicenter nationwide study and demonstrated the phenotypic differences according to onset age and severity. Considering the findings that the early-onset group is more severe and accompanied by more systemic allergic diseases, early management should be emphasized in young children and infants.